Fuel Heater delete and truck surging

[renjaminfrankln]

Problem solved by a new mechanical lift pump. Also, no air gets in the lines overnight any more. The fuel in the filter used to drain back pretty fast. I probably need to check the oil to make sure it does not smell like diesel fuel.

 

[Thewespaul]

Sounds like the pump wasn’t checking the fuel, these mechanical lift pumps are designed to be a check valve for the fuel system but they hardly ever do after a good amount of mileage

 

[renjaminfrankln]

Ah crap.

Problems are back. I drove the truck all weekend, probably 150 miles, lots of highway, not a hiccup. Fired right up even after sitting overnight, and ran great.

This morning it cranked right up after sitting overnight. Drove it about an hour to a junkyard to pick up some parts for another project. Shut the truck down for about 10 mins, fired it up and it acts like it had air bleed back into the fuel lines. Stumbles around for a bit and then smoothed out. Drove from there to work. Ran fine on the way, about an hour. Shut down at work.

Start up after sitting for a few hours to go to lunch. Cranks up but quickly coughs and sputters like its getting the air out of the lines. After 20-30 seconds it smooths out some and I back out of the parking spot. Take off in 2nd, running fine, go around the corner, hit a straight-away, push in the clutch to shift to 3rd, and the engine dies, a new symptom.

Now, when on the gas under load, it runs absolutely fine. I would think there might be a fuel delivery issue, but it pulls great through the gears. However if you are in neutral and give it some gas, it will not go straight to a constant RPM, but wander around a bit.

When driving, if you rev to 2000 RPM, then push in the clutch and let the RPM drop, it will straight up die. Cranks right back up and idles smoothly like nothing ever happened. It died about 5 times on a 2 mile trip to lunch.

New mechanical lift pump
New hard fuel supply line from the FSV forward.
No leaks observed from mechanical pump to filter head. No leaks observed on filter head or filter to IP line, no leaks observed on injection or return lines on top of the engine.

Right now i'm thinking it could be one of a few things.

Sucking a lot of air from somewhere between the FSV and the front tank. I have never run it on the rear tank as the previous owner told me that the return lines will pressurize if you select the rear tank. I have not had a chance to troubleshoot that yet. I have a replacement FSV but I have been fixing other stuff on the truck and just dealing with the reduced fuel capacity for now.

A vent problem on the front tank
This could explain some things if the vent is clogged. I'm going to pull the fuel cap off and see if that does anything

Clogged fuel pickup from showerhead parts
Could explain why the truck dies after being revved up. The fuel pressure gets low due to a restriction and it does not have time to "catch up" as the RPM's fall, when the RPM's get down to idle the IP has low lift pressure and it stalls.

I am ordering a fuel pressure gauge so i'll have that in a day or two. I also have an old Filter to IP hard line that I cut and spliced in a few inches of clear fuel line, so I can see if air is getting to the injection pump.

I'll post a video of it running here in a sec.

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[renjaminfrankln]

By the way, when dealing with intermittent gremlins, it helps to keep reminding yourself that it is only a machine, there is a mechanical problem somewhere, you just have to find it. It is not cursed and it does not hate you. Keep telling yourself that

 

[renjaminfrankln]

I have a solid 3-4 psi at the filter head and there are no air bubbles going to the IP. No leaks in the injector lines and the injectors were all recently pop tested.

Let me know if y'all can think of anything else to check. The IP is a pensacola reman with 1000 miles on it. If that is the problem, im going to send it back and buy one from Wes.

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[Thewespaul]

Hopefully not that pump going out, but you’ve done a good job narrowing it down so far. Try taking the truck for a drive with the gas caps off and see if the issue persists. Watching the clear hose, rev the engine hard a few times to put some load on it then let it idle for 2 minutes while you stare down the hose for any bubbles at all. If it passes both of those tests then there’s a couple checks on the pump to see if it’s experienced a few oddball mechanical failures. First take off the triangle inspection plate on the side of the pump to reveal the fuel screw with the engine rotated to the correct position. Using an Allen move the fuel screw in and out a flat in each direction and return it back to its original location. It should be tight in both directions and shouldn’t bind or have less resistance either way you turn it. I have seen it before where this screw will come loose inside the pump and when rotating at high rpm’s the fuel adjustment will be moving all over the place causing some weird symptoms like what youre experiencing. While you’re there operate the throttle by hand with the cable disconnected, should be smooth throughout the entire throw. No binding or tight spots. Last ditch effort before pulling that pump off, take the top cover off and take some close pictures with it off and post it here. Fingers crossed, hope we can find something obvious

 

[Thewespaul]

One more thing, with the engine idling, break this nut loose circled in red. Using a 3/16 Allen, play with the adjustment and see if your issue with the hovering rpms and drooping rpms change better or worse. Just another thing that can give us a clue to the issue.

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[renjaminfrankln]

Hopefully not that pump going out, but you’ve done a good job narrowing it down so far. Try taking the truck for a drive with the gas caps off and see if the issue persists. Watching the clear hose, rev the engine hard a few times to put some load on it then let it idle for 2 minutes while you stare down the hose for any bubbles at all. If it passes both of those tests then there’s a couple checks on the pump to see if it’s experienced a few oddball mechanical failures. First take off the triangle inspection plate on the side of the pump to reveal the fuel screw with the engine rotated to the correct position. Using an Allen move the fuel screw in and out a flat in each direction and return it back to its original location. It should be tight in both directions and shouldn’t bind or have less resistance either way you turn it. I have seen it before where this screw will come loose inside the pump and when rotating at high rpm’s the fuel adjustment will be moving all over the place causing some weird symptoms like what youre experiencing. While you’re there operate the throttle by hand with the cable disconnected, should be smooth throughout the entire throw. No binding or tight spots. Last ditch effort before pulling that pump off, take the top cover off and take some close pictures with it off and post it here. Fingers crossed, hope we can find something obvious

Thanks. Fuel cap not the issue, tried that already.

I ran the engine quite a bit (not on video) and did not see any bubbles at all. I'll recheck this of course.

I'll check the screws and pull the top cover off. Before I installed the pump, I turned the fuel up 1/4 turn of the allen screw per a Banks turbo install manual I found. The screw felt like I would expect a carb or pump adjustment screw to feel, steady even resistance when turning it.

 

[renjaminfrankln]

What are the odds that its something obvious and easy to fix?

I sent Pensacola that video and they offered to give me a refund and give me back a core, which seems fair enough. I ask only because I feel like it will take me about as much time to fiddle with all that stuff as it would for me to pull the pump off.

 

[Thewespaul]

Hard to say, with an offer like that I’d go ahead and pull it

 

[IDIBRONCO]

I would too. I'd probably put a note in with their pump that said something about this one only being good for a core too. I probably wouldn't recommend for anybody to do this. I may not even do it with their generous offer. It would cross my mind several times though.

 

[hadley000]

Problem solved by a new mechanical lift pump.

Does the pump happen to be a Spectre pump? I had one go bad after 200 miles and did the same thing as yours.

 

[renjaminfrankln]

I would too. I'd probably put a note in with their pump that said something about this one only being good for a core too. I probably wouldn't recommend for anybody to do this. I may not even do it with their generous offer. It would cross my mind several times though.

Im a little confused what you are suggesting?

Does the pump happen to be a Spectre pump? I had one go bad after 200 miles and did the same thing as yours.

Carter, and its confirmed to be working fine via pressure gauge.


I'll start the removal of the pump this evening, may get it out tonight with a little luck.

 

[IDIBRONCO]

Im a little confused what you are suggesting?

That it seems to be only good for a core. Since they are giving your money back plus a core pump, it would probably be best to not mention it to them. I'd honestly be very happy with how they are handling your situation. There's probably a lot of places that would give you a run around.

 

[renjaminfrankln]

I'd honestly be very happy with how they are handling your situation. There's probably a lot of places that would give you a run around.

True. I have not had good luck with their parts, but I have no complaints about the customer service.

Pump is out, drained and ready to ship. Only took me an hour and a half. I am reluctantly becoming a good diesel mechanic.